depth differences.

I’m using the free version of Unity.

I’m trying to do pixel fog effects.

My scene is rendered, and I have an object set up to render to add the pixel fog effect, I want to be able to place it in the scene so I can set up fog ‘windows’.

I need to access the current depth in the frame buffer and the depth of the rendering object to get the difference to apply a fog to the rendered scene.

Anybody got any helpful pointers?

[Edit]
Ok so I have tweaked the shader from soft particles to do what I want but it’s not blending using depth.

I used camera.depthTextureMode to enable the depth texure drawing, but how do I access the data in this render in the free version.

Using _GlobalDepthTexture doesn’t work…

This is only possible in Unity Pro because of the Render Textures.